This invention relates to steering of tractors and more particularly, to the steering of tractors which include steering clutches and steering brakes.
In track-type tractors steering is accomplished by interrupting the drive to the drive wheel or sprocket on one side or the other of the tractor, and may be assisted by applying a brake selectively to the one or other of the drive components. Examples of such systems are disclosed in U.S. Pat. No. 3,895,703, and U.S. Pat. No. 3,899,058, both assigned to the assignee of this invention. Further of interest are U.S. Pat. No. 2,433,443, U.S. Pat. No. 3,376,846, and British Pat. No. 1,218,526, each of which disclose a system of the above generally described type. While such systems have been found relatively effective for the particular environmental structures with which they are to be combined, it is to be understood that it is always highly desirable to further increase the operating efficiency of such a system to provide particular results, meanwhile insuring that such a system is simple, relatively inexpensive, reliable, and highly efficient. Particular attention should be paid to the ease of construction of such a system, combined with the overall simplicity thereof. Additionally, attention should be paid to providing the operator of the vehicle information of the status of the system and its effect on the vehicle during the continuing actuation process of a system. That is, for example, it is deemed highly desirable that the operator of such a system be aware of the fact that he is in a transition stage between one drive state of the vehicle and another, or that he is approaching such a drive transition stage. While certain of the above systems attempt to deal with such problems, it will be understood that particular structure which provides the operator with proper and accurate information as to the state thereof is highly desirable.
Of more general interest in this area is U.S. Pat. No. 2,989,986 (assigned to the assignee of this invention), which discloses a hydraulic control valve for actuating steering clutches.